The effects of micro-defects and crack on the mechanical properties of metal fiber sintered sheets

• Published in: International journal of solids and structures Vol. 51; no. 10; pp. 1946 - 1953
• Main Authors: Jin, M.Z., Zhao, T.F., Chen, C.Q.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.05.2014
• Subjects: Computer simulation; Defects; Elastoplastic properties; Fibers; Finite element; Fracture mechanics; Fracture toughness; Mathematical analysis; Mathematical models; Porous metal fiber sintered sheets; Separation; Sheet metal; Elastoplastic properties; Porous metal fiber sintered sheets; Defects; Fracture toughness; Finite element
• ISSN: 0020-7683; 1879-2146
• DOI: 10.1016/j.ijsolstr.2014.02.004

•The mechanical properties of MFSSs with micro-defects and crack are investigated.•Finite element and analytical models are developed for the effects of micro-defects.•Good agreement between numerical and analytical predictions is obtained.•The crack tip plasticity and toughness of cracked MFSSs are simulated and measured.•Obtained results show that MFSSs are not sensitive to the micro-defects and crack. The effects of three types of defect (i.e., two micro defects—broken fibers and separation of fiber joints and one macro defect—crack) on the mechanical properties of porous metal fiber sintered sheets (MFSSs) are investigated by a combination of numerical simulation, analytical modeling, and experimental test. All simulations are based upon the previously developed micromechanics random beam model (Jin et al., 2013). Broken fibers are realized by removing cell edges (i.e., fibers between two joints) in an otherwise perfect model. Their induced decreases in the elastic moduli and strengths are found to be much lower than those of two dimensional (2D) foams and Kagome grids. For the defect in the form of separation of fiber joints, both analytical and numerical models are developed. The predicted linear decreases in the moduli and strengths (except for the compressive strength) with increasing number of separated fiber joints indicate that MFSSs be insensitive to the defect of joint separation. To explore the effect of crack, fracture toughness of MFSSs is measured and is found to be significantly higher than that of metal foams of the same relative density (i.e., volume fraction of the constituent solid material). The underlying ductile mechanism of MFSSs is further investigated by numerical simulations, showing that plastic deformation spreads all over the fibers in ligament rather than concentrates around crack tip. This study shows that MFSSs are superior in view of their resistance to the considered micro-defects and crack.